Root-control barriers have become widely used in the prevention of damage by tree roots to sidewalks and other static structures. There are, however, practical problems and expenses associated with use of those control barriers marketed prior to the present invention. Notably, these problems relate to (a) shipment, storage and inventory management of the control barriers, and (b) labor and difficulty at the job site.
Relative to the problems designated under (a) above, the pioneer and still widely-used control barrier is a hollow frustum of a pyramid, having internal vertical ridges. These are shipped and stored in nested condition. During shipment and storage, the ridges of one control barrier cannot be interleaved, at all, with those of another control barrier. At the job site, the control barriers are always a closed-loop configuration of predetermined size; they cannot be used in single-elongate configuration along a sidewalk, for example.
Another type of control barrier is shipped and stored in large rolls, being wound up in the manner of clock springs. The ridges of such volutes cannot be interleaved at all. Furthermore, the circular configuration means that there is inherently space wasted between adjacent rolls in that adjacent rolls can only touch each other along lines instead of surfaces.
Another type of control barrier employs individual panels adapted to be connected together by extruded connectors, and having ridges on one side thereof. These can be shipped and stored in stacked relationship and with their ridges interleaved to increase packing density. However, the individual unconnected panels, and associated extrusions, are not adapted for closed-loop configurations in shapes other than circular or curved. Furthermore, they are subject to problems indicated above under (b), in that they all must be connected together at the job site.
For years, the best and widely used manner of connecting the panels together has been by the extruded connectors; these slide laterally along flange portions at the ends of endwise-related panels. Making these connections, even though no adhesive is required, has required a substantial amount of work at the job site. Furthermore, the connectors are not such as to permit making of corners at the regions where the ends (end edges) of panels come into proximity with each other. Instead, the connectors only permit the ends to be in line with each other, so that if a closed-loop configuration is desired it is--with these elements--necessarily a substantial circle and not a square, polygon, etc.
Relative to the above-indicated continuous barrier wound in a roll or volute, this generates particular difficulties at the job site. For example, it is difficult to install such a barrier in a narrow trench that has been made by a root-pruning machine. Such trenches are often only a few inches wide. To unroll a substantial length of previously-rolled barrier, and which has a memory tending to make it remain in rolled condition, and install such barrier in a narrow trench, can be a difficult job.
Another major factor, relative to barriers in roll or volute form, relates to wastefulness. For example, if it is desired that the barrier be twelve feet long, and the roll is eighteen feet long, there is a six-foot strip left over after the barrier has been cut. This six-foot strip must usually either be discarded or connected to other "waste" or full strips by a gluing operation.
An additional problem at the job site relates to obtaining the desired length of single-elongate barrier even when unskilled labor is employed. It would be highly desirable to know that a certain number of pre-connected sections or panels create a barrier of predetermined length along a sidewalk, for example.
Relative to inventory management, it would be especially desirable to have a single type of construction that could be used either in single-elongate configuration as, for example, along a sidewalk, or in closed-loop configuration of square or other polygonal cross section. This single type could be shipped and stored by wholesalers, contractors, etc., and then the decision could be made as to how much of the single type of construction is to be single-elongate and how much is to be closed-loop square or other polygonal (or curved) shape.